Police said two bombs blew up in quick succession in Karbala, where the pilgrims had congregated at the shrine of Imam Hussein.

The people were marking Arbaeen -- the end of the 40-day mourning period at the close of Ashura.

Ashura commemorates the martyrdom of Hussein, the grandson of the Prophet Mohammed who was killed in battle in Karbala in 680 A.D. That event helped create the schism between Sunnis and Shiites, the two main Muslim religious movements.